1. Field of the Invention
This invention relates to a semiconductor device, and more particularly to a semiconductor rectifier having high breakdown voltage, low loss and high speed characteristics.
2. Description of the Related Art
Various types of semiconductor devices have been proposed for improving the characteristics of semiconductor rectifiers, etc, especially the switching speed, and the forward and reverse characteristics.
FIG. 1 is a sectional view of a conventional Schottky barrier semiconductor device. Numeral 11 indicates one conductivity type semiconductor substrate having a high impurity concentration such as an N.sup.+ -type semiconductor substrate; 12 an N-type semiconductor layer; 13 a guard ring region of a P-type semiconductor layer; 14 an insulting film such as SiO.sub.2 ; 15 a metal electrode making Schottky barrier contact with the N-type semiconductor layer 12; 16 an ohmic metal electrode provided on the N.sup.+ -type semiconductor substrate 11; A an anode; and C a cathode, respectively.
The Schottky barrier semiconductor device of FIG. 1 is well known for increasing the breakdown voltage. However, such a device has an insufficient efficiency because the reverse leakage current is high in the rectifying operation.